The present invention relates to a method of making connections in liquids and an apparatus therefor in which the electrical connections are made in the liquids by the use of connectors capable of having their electrical connection portions attached to and detached from each other without being affected by the ambient liquids.
In general, in the sodium of a fast breeder reactor, the water of a light-water nuclear reactor and the various liquids of chemical plants and the like, connectors in the transmission paths of electric signals, fluid pressure signals etc. need to be attached and detached without being affected by the ambient liquids.
By way of example, in the experimental reactor "JOYO" of the Power Reactor and Nuclear Fuel Development Corporation, various irradiation tests are conducted using a fuel assembly for irradiation which has the same configuration as that of an ordinary fuel assembly for burnup. In such an experiment, it is required that the irradiating fuel assembly be placed in and removed from the nuclear reactor.
First, a fuel shuffling operation in a conventional nuclear reactor will be described with reference to FIG. 15.
FIG. 15 is a view for explaining the fuel shuffling operation of the nuclear reactor, in which numeral 70 designates a reactor vessel, numeral 71 a fuel assembly for burnup, numeral 72 sodium liquid, numeral 73 a reactor core, numeral 74 a fuel assembly for irradiation, numeral 75 an irradiating-fuel-assembly manipulator, numeral 76 a fuel handling machine, numeral 77 a rotary plug, and numeral 78 a fuel loader/unloader.
In the illustrated reactor, the burnup fuel assembly 71 is transferred within the reactor vessel 70 by the combination of the fuel handling machine 76 and the rotary plug 77, while it is loaded into or unloaded from the reactor vessel 70 by the fuel loader/unloader 78.
FIG. 16 is a view for explaining the charging of the irradiating fuel assembly in the reactor, the left side of which shows the state under test and the right side the state for unloading the fuel assembly. In the Figure, numeral 79 designates electric wires for measurement, numeral 80 the top of the irradiating fuel assembly, numeral 81 a holding claw, and numeral 82 a cutter.
In a case where the irradiating fuel assembly 74 is to be loaded in the reactor, it cannot be handled with the fuel handling machine 76 or the fuel loader/unloader 78 because the measuring electric wires 79 for the measurement outside the reactor extend out of the top of the irradiating fuel assembly 74, and because no technique for connecting and disconnecting the measuring electric wires 79 in the sodium liquid 72 within the reactor vessel 70 without being affected by the liquid is available at present. Therefore, the irradiating fuel assembly 74 is inserted from above the rotary plug 77 into the core 73 within the reactor vessel 70 along with the irradiating-fuel-assembly manipulator (referred to as the "manipulator" hereinafter) 75 in a state where the irradiating fuel assembly 74 is unitarily coupled to the manipulator 75 through the holding claws 81 provided at the fore end of the manipulator 75 and the measuring electric wires 79 are arranged down to the interior of the irradiating fuel assembly 74 without any connective parts.
After the test, the irradiating fuel assembly 74 cannot be extracted through the reverse procedure because it will be radioactive. Therefore, the cutter 82 provided at the fore end of the manipulator 75 is driven to cut the measuring electric wires 79 as shown on the right side of the figure, whereupon the holding claws 81 are released to separate the manipulator 75 and the irradiating fuel assembly 74. Under these conditions, the top 80 of the irradiating fuel assembly 74 can be handled with the fuel handling machine 76 and the fuel loader/unloader 78, so that the irradiating fuel assembly 74 can be taken out by the same means as that used for the ordinary burnup fuel assembly 71.
However, this prior-art system for handling the irradiating fuel assembly has the following problems:
(1) Since the measuring electric wires are cut at the fore end of the manipulator, the sodium liquid, which is electrically conductive, intrudes into the measuring electric wires and breaks down the insulation, thus making it necessary to lay measuring electric wires again for the next test. However, since the manipulator has a slender structure, it must be cut into small sections in order to exchange the measuring electric wires, and this method is costlier than the fabrication of a new manipulator. Eventually, the manipulator is fabricated for each fuel assembly for irradiation, thereby raising the cost of the irradiation test.
(2) As a result, the manipulators inevitably have a one-to-one relationship with respect to the irradiating fuel assemblies. Even if the manipulator and the irradiating fuel assembly are later scrapped, they need to be washed on each occasion on account of the adhesion of sodium. This increases the amount of radioactive waste liquid. Moreover, it is required that the manipulator be handled as a radioactive waste on account of its use inside the nuclear reactor. This increases the quantity of solid waste.
(3) When the irradiating fuel assembly with the measuring electric wires is inserted into the reactor before the fuel shuffling operation which requires the turning of the rotary plug, the latter cannot be turned for fear of severing the wires. Accordingly, the insertion of the irradiating fuel assembly must be carried out later than the fuel shuffling operation of the reactor core, and restrictions are imposed on the preparation of a reactor running schedule.